A control method based on building heat comprehensive utilization

Abstract

The application discloses a kind of control method based on building heat comprehensive utilization, comprising the following steps: S1: temperature perception;S2: local control;S3: global scheduling;S4: collaborative operation.The present application is through the cascade utilization of steam condensate waste heat of reclaimed water and steam, and the waste heat recovery utilization rate is significantly improved, reduces low-level thermal energy waste, reduces the demand for fossil energy replacement, relies on multi-heat source collaborative regulation and valley time heat storage strategy, the length of time of air source heat pump and water source heat pump unit low-efficiency operation is reduced, unit start-stop frequency is reduced, and the overall operation energy consumption of the system is reduced by 20%-30%, through the collaborative control of large and small water tanks and double heat source dynamic regulation, the fluctuation range of domestic hot water supply temperature is controlled within ±2℃, the water level guarantee rate is improved to more than 99.5%, the user end hot water supply response time is ≤3s, completely solve the problem of high and low water temperature in the prior art, water supply is interrupted during peak water consumption period and other problems, reduce carbon dioxide, sulfur dioxide and nitrogen oxides emissions, meet the requirements of "double carbon" policy.

Description

Technical Field

[0001] This invention belongs to the field of heating, ventilation and air conditioning technology, and specifically relates to a control method based on the comprehensive utilization of building heat. Background Technology

[0002] Currently, in the fields of HVAC and water supply and drainage, systems for the comprehensive utilization of building heat typically adopt a decentralized control mode: waste heat recovery from greywater is mostly limited to a single heat exchanger device, and the waste heat from steam condensate is not linked to the heat pump system for circulation; air source heat pumps and water pump heat pump units start and stop independently, without coordinated adjustment based on changes in ambient temperature and real-time building heat load; and there is a lack of intelligent control mechanism for heat transfer between domestic hot water heating tanks and hot water storage tanks. However, the aforementioned existing technologies have significant drawbacks: 1. Low energy utilization rate: the waste heat of greywater and steam condensate is not fully recovered and utilized, and direct discharge results in energy waste. Second, the system has high energy consumption and the independent operation of multiple heat source devices lacks coordinated optimization, resulting in frequent start-ups and shutdowns or inefficient operation of the unit. Third, the unstable hot water supply and the unreasonable heat distribution in the water tank room affect the user experience.

[0003] The core issue is that the existing control logic has not integrated and optimized various heat sources such as waste heat from greywater, waste heat from steam condensate, air source heat pumps, and water source heat pumps. It has not established a dynamic adjustment model based on real-time heat load, ambient temperature, and waste heat resources, making it impossible to achieve efficient heat distribution and precise utilization, and thus failing to simultaneously meet the multiple requirements of building energy conservation, efficient system operation, and user comfort. Summary of the Invention

[0004] In view of the problems raised in the background art above, the purpose of the present invention is to provide a control method based on the comprehensive utilization of building heat.

[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows: A control method based on comprehensive utilization of building heat, characterized by the following steps: S1: Temperature sensing, using temperature sensors to collect real-time temperature data of greywater inlet and outlet, steam condensate inlet and outlet, heat pump unit inlet and outlet, domestic hot water supply and return mains and user terminal water supply points, and transmit the data to the DDC controller. S2: Local control. The DDC controller receives temperature sensing data, performs calculations based on preset collaborative control logic, and issues pipeline on / off, flow regulation, and equipment start / stop commands to actuators such as electric valves and circulating water pumps. At the same time, it uploads local operating data to the building control system and receives remote control commands from the building control system. S3: Global scheduling. The building control system establishes a communication link with the DDC controller via Ethernet. It also integrates multi-heat source operating parameters, pipeline temperature distribution data, user heat load data, and electricity price time information. The building control system has a built-in load prediction algorithm that can optimize the start-up sequence and switching strategy of each heat source based on historical load curves and ambient temperature prediction data. S4: Collaborative operation, executing control logic for collaborative storage and supply of hot water in large and small water tanks, cascade utilization of waste heat from greywater and steam condensate, collaborative heating by air source and water source heat pumps, and mixed heating by water source heat pumps and boilers, to achieve efficient distribution and precise utilization of building heat.

[0006] Further specifying that in S1, the temperature sensor is a Pt100 high-precision temperature sensor, which is installed at the inlet and outlet of reclaimed water, the inlet and outlet of steam condensate, the inlet and outlet of air source heat pump unit, the inlet and outlet of water source heat pump unit, the domestic hot water supply main, the return water main, and the user terminal water supply point. The measurement range is -20℃ to 100℃, the measurement accuracy is ±0.2℃, and the temperature data is transmitted to the DDC controller via RS-485 bus.

[0007] Furthermore, the temperature sensor can also be a thermocouple sensor with a measurement range of 0℃ to 80℃ and an accuracy of ±0.3℃, and the signal is transmitted to the DDC controller via a K-type thermocouple.

[0008] Further specifying, in S2, the actuators include an electric three-way valve, a cold water supply electric two-way valve, a circulating water pump, and a heat source output valve, all of which are industrial-grade programmable actuators with a response time ≤1s and bidirectional communication with the DDC controller via the Modbus RTU protocol.

[0009] Further specifying that in S3, the load prediction algorithm adopts an LSTM neural network model, which can predict the building's heat load demand 2 to 4 hours in advance based on historical load curves and ambient temperature prediction data.

[0010] Furthermore, the DDC controller has a built-in 32-bit industrial-grade microprocessor, supports multiple protocol compatibility, can upload operating data to the building control system, and can receive remote control commands from the building control system.

[0011] Further specifying, in S4, the control logic for the coordinated storage and supply of hot water by the large and small water tanks is as follows: Operating schedule planning: Air source heat pump units should be prioritized to operate during off-peak electricity pricing periods (00:00 to 08:00) to reduce operating costs; Heating circulation control: After the heat pump unit starts, it circulates and heats the water in the heating tank. When the temperature sensor detects that the water temperature in the heating tank has reached the set value (55℃±1℃), it sends a signal to the DDC controller. The DDC controller controls the electric three-way valve to switch, closes the circulation passage on the side of the heating tank, and opens the pipeline valve on the side of the hot water storage tank to transport the hot water in the heating tank to the hot water storage tank. Water replenishment control: When the level sensor (linked with the temperature sensor) detects that the water level in the heating water tank has dropped to the set lower limit (30% of the tank volume), the DDC controller sends a command to the cold water replenishment two-way valve to start the water replenishment process until the water level rises to the set upper limit (80% of the tank volume), at which point the water replenishment valve automatically closes. Cyclic start-stop control: When the temperature sensor detects that the water temperature in the heating tank is below 53℃, the DDC controller controls the electric three-way valve to switch back to the heating tank side passage, closes the storage tank side valve, and the heat pump unit restarts the heating process until the water level in the storage tank reaches the set upper limit (90% of the tank volume), completing the off-peak heat storage.

[0012] Further specifying, in S4, the control logic for the cascade utilization of waste heat from greywater and steam condensate is as follows: Primary waste heat utilization: Steam condensate exchanges heat with domestic hot water return water through a plate heat exchanger. Temperature sensors monitor the steam condensate outlet temperature in real time. When the temperature drops to 48℃±0.5℃, a signal is sent to the DDC controller. The DDC controller immediately issues an instruction to close the steam condensate side circulating water pump and inlet / outlet valves, and simultaneously open the greywater side circulating water pump and inlet / outlet valves, switching to the secondary waste heat utilization mode. Secondary waste heat utilization: Temperature sensors monitor the temperature of domestic hot water return water. When the return water temperature is lower than 46℃±0.5℃, the DDC controller sends a start command to the water source heat pump unit, the reclaimed water tank circulation pump and the corresponding valves. The water source heat pump unit uses the waste heat from the reclaimed water tank as a heat source for heating. Low temperature protection control: When the temperature sensor detects that the water temperature in the greywater tank is below 10℃±0.5℃, it is determined that the waste heat resources are insufficient. The DDC controller issues an instruction to shut down the greywater system circulating water pump and inlet and outlet valves, open the greywater system drain valve, and discharge the low-temperature water to avoid inefficient operation or failure of the water source heat pump unit due to insufficient heat source.

[0013] Further specifying, in S4, the coordinated heating control logic of the air source heat pump and the water source heat pump is as follows: Heat source switching trigger condition: The critical value is 10℃±0.5℃ of water temperature in the middle water tank, which is monitored in real time by the temperature sensor and fed back to the DDC controller; Air source heat pump start-up mode: When the water temperature in the pool is below 10℃±0.5℃, the water source heat pump unit lacks an effective heat source. The DDC controller sends a command to the air source heat pump unit to start the heating mode and output hot water at 35℃±1℃ as an auxiliary heat source for the water source heat pump unit to ensure the stable operation of the water source heat pump unit. Independent heating mode of water source heat pump: When the water temperature in the middle water tank rises to above 10℃±0.5℃, the temperature sensor sends a signal to the DDC controller. The DDC controller issues an instruction to start the circulating water pump in the middle water tank and the corresponding electric valve, shut down the air source heat pump unit, and switch to the independent heating mode of the water source heat pump unit to make full use of the waste heat of the middle water.

[0014] Further specifying, in S4, the control logic for the dual heat source hybrid heating of the water source heat pump and the boiler is as follows: Parameter preset stage: The core control parameters are preset in the DDC controller. The target supply water temperature for the primary circulation is 45℃±1℃, and the supply water temperature of the water source heat pump is set to 47℃±1℃ (with a 2℃ temperature loss allowance). The normal monitoring range for the return water temperature of the water source heat pump is 43℃~47℃. Two time thresholds are set: when the return water temperature is below 43℃, the boiler is started after continuous monitoring for 10 minutes (±30s); when the return water temperature exceeds 47℃, the boiler is stopped after continuous monitoring for 5 minutes (±30s). The boiler is set to two operating modes: low fire and medium fire. The heating power of the low fire mode is 50% of the rated power, and the heating power of the medium fire mode is 80% of the rated power. Real-time monitoring phase: The DDC controller collects the return water temperature data of the water source heat pump at a frequency of 1 time per minute through the temperature sensor, with a data sampling period of 100ms, to ensure the continuity and accuracy of the temperature data; Collaborative Start-up Phase: When the return water temperature of the water source heat pump is detected to be below 43℃ and this state lasts for ≥10 minutes, it is determined that the water source heat pump is not providing enough heat. The DDC controller automatically sends a start-up command to control the boiler to start at a low flame level and work in synergy with the water source heat pump to quickly increase the temperature of the primary circulating water. Gear adjustment stage: After the boiler runs at low fire for 10 minutes, the DDC controller collects and analyzes the return water temperature again. If the return water temperature is still below 43℃, a gear adjustment command is issued to switch the boiler to medium fire gear to increase heating power. If the return water temperature rises to the range of 43℃~47℃, the low fire gear is maintained for continuous coordinated heating to avoid redundant energy consumption. Dynamic shutdown and circulation phase: The temperature sensor continuously monitors the return water temperature. If the temperature exceeds 47℃ and lasts for ≥5 minutes, it is determined that the total heat supply is excessive. The DDC controller immediately sends a shutdown command, the boiler stops running, and only the water source heat pump independently heats the water. Subsequently, the return water temperature is adjusted according to changes in ambient temperature or hot water consumption. If the return water temperature falls below 43℃ again and meets the time threshold, the above start-up and adjustment process is repeated to achieve dynamic coordination of the two heat sources and ensure that the temperature of the primary circulating water is stable within the target range of 45℃±1℃.

[0015] The beneficial effects of this invention are as follows: 1. Significantly improved efficiency of waste heat resource utilization: Through the cascade utilization of waste heat from greywater and steam condensate, the waste heat recovery and utilization rate is significantly improved, reducing the waste of low-grade heat energy and lowering the demand for fossil energy substitution.

[0016] 2. Significantly reduced system operating energy consumption: Relying on multi-heat source coordinated regulation and off-peak heat storage strategy, the inefficient operation time of air source heat pump and water source heat pump units is reduced, the start-up and shutdown frequency of the units is reduced, and the overall system operating energy consumption is reduced by 20% to 30%.

[0017] 3. Significantly enhanced stability of hot water supply: Through coordinated control of large and small water tanks and dynamic adjustment of dual heat sources, the fluctuation range of domestic hot water supply temperature is controlled within ±2℃, the water level guarantee rate is increased to over 99.5%, and the hot water supply response time at the user end is ≤3s, completely solving the problems of fluctuating water temperature and supply interruption during peak water usage periods in existing technologies.

[0018] 4. Significant social benefits: It reduces carbon dioxide emissions, sulfur dioxide and nitrogen oxide emissions annually, which meets the requirements of the "dual carbon" policy. At the same time, it reduces the total energy consumption of buildings and provides technical solutions for similar building heat utilization systems, which have broad application value. Attached Figure Description

[0019] The present invention can be further illustrated by the non-limiting embodiments given in the accompanying drawings; Figure 1 This is a schematic flowchart of a control method based on the comprehensive utilization of building heat according to an embodiment of the present invention; Detailed Implementation To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0020] like Figure 1 As shown, a control method based on comprehensive utilization of building heat according to the present invention includes the following steps: S1: Temperature sensing, using high-precision Pt100 temperature sensors, installed at the inlet and outlet of greywater, steam condensate inlet and outlet, air source heat pump unit inlet and outlet, water source heat pump unit inlet and outlet, domestic hot water supply main, return water main, and typical user terminal water supply points. The temperature sensor has a measurement range of -20℃ to 100℃ and a measurement accuracy of ±0.2℃. The real-time temperature data is transmitted to the DDC controller via RS-485 bus, providing accurate data support for system operation status judgment, heat source output adjustment, and load matching. S2: Local control. The DDC controller receives temperature sensing data, performs calculations based on preset collaborative control logic, and issues pipeline on / off, flow regulation, and equipment start / stop commands to actuators such as electric valves and circulating water pumps. At the same time, it uploads local operating data to the building control system and receives remote control commands from the building control system. S3: Global Scheduling. The building control system establishes a communication link with the DDC controller via Ethernet, and integrates multi-heat source operating parameters, pipeline temperature distribution data, user heat load data, and electricity price time information. The building control system has a built-in load forecasting algorithm, which can optimize the start-up sequence and switching strategy of each heat source based on historical load curves and ambient temperature forecast data. It also provides a visual human-machine interface (HMI) to support maintenance personnel to manually modify operating parameters and intervene in the system's operating status in emergencies. It interfaces with the building's existing energy management system (EMS) through the BACnet protocol to achieve data interoperability and collaborative management, improving the compatibility of the upgraded system. S4: Collaborative operation, executing control logic for collaborative storage and supply of hot water in large and small water tanks, cascade utilization of waste heat from greywater and steam condensate, collaborative heating by air source and water source heat pumps, and mixed heating by water source heat pumps and boilers, to achieve efficient distribution and precise utilization of building heat.

[0021] In this embodiment, taking the renovation of the heat utilization system of Chongqing Jinke Hotel as an example, the specific implementation steps are as follows: Hardware deployment: Pt100 temperature sensors are installed at nodes such as reclaimed water, steam condensate, heat pump units, and hot water supply and return mains. Electric three-way valves, circulating water pumps and other actuators are configured. DDC controllers are deployed in the central control room. The building control system is connected to the hotel’s original EMS system via the BACnet protocol. Large and small water tank control: 00:00~08:00 The air source heat pump starts to heat the water tank. When the water temperature reaches 55℃±1℃, it is delivered to the hot water storage tank. When the water level in the heating tank is 30%, water is added to 80%. Heating is restarted when the water temperature is below 53℃. Heating stops when the hot water storage tank is 90% full. Waste heat utilization: Steam condensate first exchanges heat with domestic hot water return water. When the temperature drops to 48℃±0.5℃, the greywater system is switched on. When the return water temperature is below 46℃±0.5℃, the water source heat pump is started. When the greywater tank temperature is below 10℃±0.5℃, the greywater system is shut off and sewage is discharged. Dual heat pump synergy: When the water temperature in the middle water tank is below 10℃±0.5℃, the air source heat pump starts to provide an auxiliary heat source of 35℃; when the temperature is above this, the water source heat pump operates independently. Dual heat source heating: The preset target temperature for the primary circulating water is 45℃±1℃. If the return water temperature is below 43℃, the boiler will start on low heat for 10 minutes. If the target temperature is not reached after 10 minutes, the boiler will switch to medium heat. If the temperature exceeds 47℃, the boiler will stop for 5 minutes to ensure a stable water supply temperature.

[0022] Among them, the control logic for the coordinated storage and supply of hot water by large and small water tanks is as follows: Operating schedule planning: Air source heat pump units should be prioritized to operate during off-peak electricity pricing periods (00:00–08:00) to reduce operating costs. Heating circulation control: After the heat pump unit starts, it circulates and heats the water in the heating tank. When the temperature sensor detects that the water temperature in the heating tank reaches the set value (55℃±1℃), it sends a signal to the DDC. The DDC controller controls the electric three-way valve to switch, close the circulation passage on the side of the heating tank, and open the pipeline valve on the side of the hot water storage tank to transport the hot water in the heating tank to the hot water storage tank for storage. Water replenishment control: When the level sensor (linked with the temperature sensor) detects that the water level in the heating water tank has dropped to the set lower limit (30% of the tank volume), the DDC controller sends a command to the cold water replenishment two-way valve to start the water replenishment process until the water level rises to the set upper limit (80% of the tank volume), at which point the water replenishment valve automatically closes. Cyclic start-stop control: When the temperature sensor detects that the water temperature in the heating tank is below 53℃, the DDC controller controls the electric three-way valve to switch back to the heating tank side passage, closes the storage tank side valve, and the heat pump unit restarts the heating process until the water level in the storage tank reaches the set upper limit (90% of the tank volume), completing the off-peak heat storage.

[0023] Control logic for the cascade utilization of waste heat from greywater and steam condensate: Primary waste heat utilization: Steam condensate exchanges heat with domestic hot water return water via a plate heat exchanger. Temperature sensors monitor the steam condensate outlet temperature in real time. When the temperature drops to 48℃±0.5℃, a signal is sent to the DDC controller. The DDC controller immediately issues an instruction to shut down the steam condensate side circulating water pump and inlet / outlet valves, and simultaneously open the greywater side circulating water pump and inlet / outlet valves, switching to secondary waste heat utilization mode. Secondary waste heat utilization: Temperature sensors monitor the temperature of domestic hot water return water. When the return water temperature is lower than 46℃±0.5℃, the DDC controller sends a start command to the water source heat pump unit, the reclaimed water tank circulation pump and the corresponding valves. The water source heat pump unit uses the waste heat from the reclaimed water tank as a heat source for heating. Low temperature protection control: When the temperature sensor detects that the water temperature in the greywater tank is below 10℃±0.5℃, it is determined that the waste heat resources are insufficient. The DDC controller issues an instruction to shut down the greywater system circulating water pump and inlet and outlet valves, open the greywater system drain valve, and discharge the low-temperature water to avoid inefficient operation or failure of the water source heat pump unit due to insufficient heat source.

[0024] Control logic for coordinated heating of air source heat pump and water source heat pump: Heat source switching trigger condition: The critical value is 10℃±0.5℃ for the water temperature in the middle water tank, which is monitored in real time by a temperature sensor and fed back to the DDC. Air source heat pump start-up mode: When the water temperature in the pool is below 10℃±0.5℃, the water source heat pump unit lacks an effective heat source. The DDC controller sends a command to the air source heat pump unit to start the heating mode and output hot water at 35℃±1℃ as an auxiliary heat source for the water source heat pump unit to ensure the stable operation of the water source heat pump unit. Independent heating mode of water source heat pump: When the water temperature in the middle water tank rises to above 10℃±0.5℃, the temperature sensor sends a signal to the DDC controller, and the DDC controller issues an instruction: start the circulating water pump in the middle water tank and the corresponding electric valve, shut down the air source heat pump unit, and switch to the independent heating mode of the water source heat pump unit to make full use of the waste heat of the middle water.

[0025] Control logic for dual heat source hybrid heating of water source heat pump and boiler: Parameter preset stage: Preset core control parameters in the DDC controller: target supply water temperature for primary circulation is 45℃±1℃, and the water source heat pump supply water temperature is set to 47℃±1℃ (with a 2℃ temperature loss allowance); the normal monitoring range for the water source heat pump return water temperature is 43℃~47℃; set two time thresholds: when the return water temperature is below 43℃, start the boiler after continuous monitoring for 10 minutes (±30s); when the return water temperature exceeds 47℃, stop the boiler after continuous monitoring for 5 minutes (±30s); set the boiler to two operating modes: low fire and medium fire. The heating power in the low fire mode is 50% of the rated power, and the heating power in the medium fire mode is 80% of the rated power. Real-time monitoring phase: The DDC controller collects the return water temperature data of the water source heat pump at a frequency of 1 time per minute through the temperature sensor, with a data sampling period of 100ms, to ensure the continuity and accuracy of the temperature data; Collaborative Start-up Phase: When the return water temperature of the water source heat pump is detected to be below 43℃ and this state lasts for ≥10 minutes, it is determined that the water source heat pump is not providing enough heat. The DDC automatically sends a start-up command to control the boiler to start at a low flame level and work in synergy with the water source heat pump to heat the water and quickly increase the temperature of the primary circulating water. Gear adjustment stage: After the boiler runs at low fire for 10 minutes, the DDC controller collects and analyzes the return water temperature again: If the return water temperature is still below 43℃, a gear adjustment command is issued to switch the boiler to medium fire gear to increase heating power; if the return water temperature rises to the range of 43℃~47℃, the low fire gear is maintained for continuous coordinated heating to avoid redundant energy consumption. Dynamic shutdown and circulation phase: The temperature sensor continuously monitors the return water temperature. If the temperature exceeds 47℃ and lasts for ≥5 minutes, it is determined that the total heat supply is excessive. The DDC controller immediately sends a shutdown command, the boiler stops running, and only the water source heat pump independently heats the water. Subsequently, as the ambient temperature changes or the hot water consumption is adjusted, if the return water temperature falls below 43℃ again and meets the time threshold, the above start-up and adjustment process is repeated to achieve dynamic coordination of the two heat sources and ensure that the temperature of the primary circulating water is stable within the target range of 45℃±1℃.

[0026] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A control method based on the comprehensive utilization of building heat, characterized in that: Includes the following steps: S1: Temperature sensing, using temperature sensors to collect real-time temperature data of greywater inlet and outlet, steam condensate inlet and outlet, heat pump unit inlet and outlet, domestic hot water supply and return mains and user terminal water supply points, and transmit the data to the DDC controller. S2: Local control. The DDC controller receives temperature sensing data, performs calculations based on preset collaborative control logic, and issues pipeline on / off, flow regulation, and equipment start / stop commands to actuators such as electric valves and circulating water pumps. At the same time, it uploads local operating data to the building control system and receives remote control commands from the building control system. S3: Global scheduling. The building control system establishes a communication link with the DDC controller via Ethernet. It also integrates multi-heat source operating parameters, pipeline temperature distribution data, user heat load data, and electricity price time information. The building control system has a built-in load prediction algorithm that can optimize the start-up sequence and switching strategy of each heat source based on historical load curves and ambient temperature prediction data. S4: Collaborative operation, executing control logic for collaborative storage and supply of hot water in large and small water tanks, cascade utilization of waste heat from greywater and steam condensate, collaborative heating by air source and water source heat pumps, and mixed heating by water source heat pumps and boilers, to achieve efficient distribution and precise utilization of building heat.

2. The control method based on comprehensive utilization of building heat according to claim 1, characterized in that: In S1, the temperature sensor is a Pt100 high-precision temperature sensor, which is installed at the inlet and outlet of reclaimed water, the inlet and outlet of steam condensate, the inlet and outlet of air source heat pump unit, the inlet and outlet of water source heat pump unit, the domestic hot water supply main, the return water main, and the user terminal water supply point. The measurement range is -20℃ to 100℃, and the measurement accuracy is ±0.2℃. The temperature data is transmitted to the DDC controller via RS-485 bus.

3. The control method based on comprehensive utilization of building heat according to claim 2, characterized in that: The temperature sensor can also be a thermocouple sensor, with a measurement range of 0℃~80℃ and an accuracy of ±0.3℃, and the signal is transmitted to the DDC controller through a K-type thermocouple.

4. The control method based on comprehensive utilization of building heat according to claim 3, characterized in that: In S2, the actuators include an electric three-way valve, a cold water supply electric two-way valve, a circulating water pump, and a heat source output valve. All of these are industrial-grade programmable actuators with a response time of ≤1s and bidirectional communication with the DDC controller via the Modbus RTU protocol.

5. The control method based on comprehensive utilization of building heat according to claim 4, characterized in that: In S3, the load prediction algorithm uses an LSTM neural network model, which can predict the building's heat load demand 2 to 4 hours in advance based on historical load curves and ambient temperature prediction data.

6. The control method based on comprehensive utilization of building heat according to claim 5, characterized in that: The DDC controller has a built-in 32-bit industrial-grade microprocessor, supports multiple protocol compatibility, can upload operating data to the building control system, and receive remote control commands from the building control system.

7. The control method based on comprehensive utilization of building heat according to claim 6, characterized in that: In S4, the control logic for the coordinated storage and supply of hot water by the large and small water tanks is as follows: Operating schedule planning: Air source heat pump units should be prioritized to operate during off-peak electricity pricing periods (00:00 to 08:00) to reduce operating costs; Heating circulation control: After the heat pump unit starts, it circulates and heats the water in the heating tank. When the temperature sensor detects that the water temperature in the heating tank has reached the set value (55℃±1℃), it sends a signal to the DDC controller. The DDC controller controls the electric three-way valve to switch, closes the circulation passage on the side of the heating tank, and opens the pipeline valve on the side of the hot water storage tank to transport the hot water in the heating tank to the hot water storage tank. Water replenishment control: When the level sensor (linked with the temperature sensor) detects that the water level in the heating water tank has dropped to the set lower limit (30% of the tank volume), the DDC controller sends a command to the cold water replenishment two-way valve to start the water replenishment process until the water level rises to the set upper limit (80% of the tank volume), at which point the water replenishment valve automatically closes. Cyclic start-stop control: When the temperature sensor detects that the water temperature in the heating tank is below 53℃, the DDC controller controls the electric three-way valve to switch back to the heating tank side passage, closes the storage tank side valve, and the heat pump unit restarts the heating process until the water level in the storage tank reaches the set upper limit (90% of the tank volume), completing the off-peak heat storage.

8. The control method based on comprehensive utilization of building heat according to claim 7, characterized in that: In S4, the control logic for the cascade utilization of waste heat from greywater and steam condensate is as follows: Primary waste heat utilization: Steam condensate exchanges heat with domestic hot water return water through a plate heat exchanger. Temperature sensors monitor the steam condensate outlet temperature in real time. When the temperature drops to 48℃±0.5℃, a signal is sent to the DDC controller. The DDC controller immediately issues an instruction to close the steam condensate side circulating water pump and inlet / outlet valves, and simultaneously open the greywater side circulating water pump and inlet / outlet valves, switching to the secondary waste heat utilization mode. Secondary waste heat utilization: Temperature sensors monitor the temperature of domestic hot water return water. When the return water temperature is lower than 46℃±0.5℃, the DDC controller sends a start command to the water source heat pump unit, the reclaimed water tank circulation pump and the corresponding valves. The water source heat pump unit uses the waste heat from the reclaimed water tank as a heat source for heating. Low temperature protection control: When the temperature sensor detects that the water temperature in the greywater tank is below 10℃±0.5℃, it is determined that the waste heat resources are insufficient. The DDC controller issues an instruction to shut down the greywater system circulating water pump and inlet and outlet valves, open the greywater system drain valve, and discharge the low-temperature water to avoid inefficient operation or failure of the water source heat pump unit due to insufficient heat source.

9. A control method based on comprehensive utilization of building heat according to claim 8, characterized in that: In S4, the coordinated heating control logic of the air source heat pump and the water source heat pump is as follows: Heat source switching trigger condition: The critical value is 10℃±0.5℃ of water temperature in the middle water tank, which is monitored in real time by the temperature sensor and fed back to the DDC controller; Air source heat pump start-up mode: When the water temperature in the pool is below 10℃±0.5℃, the water source heat pump unit lacks an effective heat source. The DDC controller sends a command to the air source heat pump unit to start the heating mode and output hot water at 35℃±1℃ as an auxiliary heat source for the water source heat pump unit to ensure the stable operation of the water source heat pump unit. Independent heating mode of water source heat pump: When the water temperature in the middle water tank rises to above 10℃±0.5℃, the temperature sensor sends a signal to the DDC controller. The DDC controller issues an instruction to start the circulating water pump in the middle water tank and the corresponding electric valve, shut down the air source heat pump unit, and switch to the independent heating mode of the water source heat pump unit to make full use of the waste heat of the middle water.

10. A control method based on comprehensive utilization of building heat according to claim 9, characterized in that: In S4, the control logic for the dual heat source hybrid heating of the water source heat pump and the boiler is as follows: Parameter preset stage: The core control parameters are preset in the DDC controller. The target supply water temperature for the primary circulation is 45℃±1℃, and the supply water temperature of the water source heat pump is set to 47℃±1℃ (with a 2℃ temperature loss allowance). The normal monitoring range for the return water temperature of the water source heat pump is 43℃~47℃. Two time thresholds are set: when the return water temperature is below 43℃, the boiler is started after continuous monitoring for 10 minutes (±30s); when the return water temperature exceeds 47℃, the boiler is stopped after continuous monitoring for 5 minutes (±30s). The boiler is set to two operating modes: low fire and medium fire. The heating power of the low fire mode is 50% of the rated power, and the heating power of the medium fire mode is 80% of the rated power. Real-time monitoring phase: The DDC controller collects the return water temperature data of the water source heat pump at a frequency of 1 time per minute through the temperature sensor, with a data sampling period of 100ms, to ensure the continuity and accuracy of the temperature data; Collaborative Start-up Phase: When the return water temperature of the water source heat pump is detected to be below 43℃ and this state lasts for ≥10 minutes, it is determined that the water source heat pump is not providing enough heat. The DDC controller automatically sends a start-up command to control the boiler to start at a low flame level and work in synergy with the water source heat pump to quickly increase the temperature of the primary circulating water. Gear adjustment stage: After the boiler runs at low fire for 10 minutes, the DDC controller collects and analyzes the return water temperature again. If the return water temperature is still below 43℃, a gear adjustment command is issued to switch the boiler to medium fire gear to increase heating power. If the return water temperature rises to the range of 43℃~47℃, the low fire gear is maintained for continuous coordinated heating to avoid redundant energy consumption. Dynamic shutdown and circulation phase: The temperature sensor continuously monitors the return water temperature. If the temperature exceeds 47℃ and lasts for ≥5 minutes, it is determined that the total heat supply is excessive. The DDC controller immediately sends a shutdown command, the boiler stops running, and only the water source heat pump independently heats the water. Subsequently, the return water temperature is adjusted according to changes in ambient temperature or hot water consumption. If the return water temperature falls below 43℃ again and meets the time threshold, the above start-up and adjustment process is repeated to achieve dynamic coordination of the two heat sources and ensure that the temperature of the primary circulating water is stable within the target range of 45℃±1℃.

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